Allow JSON messages to be returned for ClearKey.

LayoutTests/media/encrypted-media/encrypted-media-utils.js

 var console = null;
 
 function consoleWrite(text)
 {
     if (!console && document.body) {
         console = document.createElement('div');
         document.body.appendChild(console);
     }
     var span = document.createElement('span');
     span.appendChild(document.createTextNode(text));
@@ skipping 105 matching lines @@
     // currently no way to report a failed test in the test harness, errors
     // are reported using force_timeout().
     if (message)
         consoleWrite(message + ': ' + error.message);
     else if (error)
         consoleWrite(error.message);
 
     test.force_timeout();
     test.done();
 }
+
+function extractFirstLicenseKey(message)

[ddorwin, 2014/08/08 20:41:14]

As mentioned earlier, should this be extractSingleKeyIdFromMessage() along with
an assert on kids.length?

[jrummell, 2014/08/08 23:51:28]

Done.

+{
+    try {
+        var json = JSON.parse(String.fromCharCode.apply(null, new Uint8Array(message)));
+        // Decode the first element of 'kids'.
+        var decoded_key = atob(json.kids[0]);

[ddorwin, 2014/08/08 20:41:14]

FIXME: Switch to base64url

See
https://dvcs.w3.org/hg/html-media/raw-file/default/encrypted-media/encrypted-...

[jrummell, 2014/08/08 23:51:28]

Done.

+        // Convert to an Uint8Array and return it.
+        return stringToUint8Array(decoded_key);
+    }
+    catch (o) {

[ddorwin, 2014/08/08 20:41:14]

Just throw up the stack? It would mean the test is broken, so this would
probably be better.

Oh, this is for backwards compatibility and/or prefixed? If so, note that and
add a FIXME to remove it.

[jrummell, 2014/08/08 23:51:28]

Done.

+        // Not valid JSON, so return message untouched as Uint8Array.
+        return new Uint8Array(message);
+    }
+}